On Thu, 6 Nov 2025 13:52:23 GMT, Matthias Baesken <[email protected]> wrote:

>> We currently have support for LTO (link time optimization) for 
>> Hotspot/libjvm, that can be enabled as a JVM feature.
>> But for other JDK native libs, we do not have support for this feature.
>> LTO and sometimes lead to faster and also in some cases smaller binaries, so 
>> support for this might be interesting also for other libs and not only 
>> libjvm.
>
> Matthias Baesken has updated the pull request incrementally with one 
> additional commit since the last revision:
> 
>   Simplify lto flag assignment for hs in JvmFeatures.gmk

make/hotspot/lib/JvmFeatures.gmk line 182:

> 180:     JVM_LDFLAGS_FEATURES += $(LDFLAGS_LTO)
> 181:   else
> 182:     JVM_LDFLAGS_FEATURES += $(CXX_O_FLAG_HIGHEST_JVM) $(LDFLAGS_LTO)

That's better, but looking at this again, if we are now abstracting LTO support 
into `SetupNativeCompilation`, then CompileJvm.gmk/JvmFeatures.gmk should use 
that instead of adding the flags manually. What I mean is, in this conditional 
on the jvm feature `link-time-opt`, a variable should be set that causes 
`LINK_TIME_OPTIMIZATION` to be set to true for libjvm. No LTO flags should be 
explicitly added here, just the optimization flag for gcc/clang.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27976#discussion_r2499068717

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